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Chemistry Forums for Students => Physical Chemistry Forum => Topic started by: ptryon on September 12, 2011, 05:45:08 AM

Title: A basic problem
Post by: ptryon on September 12, 2011, 05:45:08 AM

I read a question asking
"What will have a greater pH, a 1moldm^-3 solution of Ba(OH)₂ or a 1moldm^-3 solution of ammonia?"

I am stuck with this one bacause barium hydroxide is only sparingly soluble (a couple of sources quote its Ksp as around 2 x 10^-3), which would lead me to say that ammonia would have the higher pH. Can Barium hydroxide even form a 1moldm^-3 solution at 298K?? Barium hydroxide is quoted has having a lower pKb than ammonia- suggesting it is a stronger base and would therefore form a solution with a higher pH than ammonia. Is this reasoning correct?

Any thoughts?

Title: Re: A basic problem
Post by: Borek on September 12, 2011, 08:37:03 AM

You may need to do calculations to be sure about exact result, but you are on the right track. No way of making 1M barium hydroxide solution.

Title: Re: A basic problem
Post by: ptryon on September 13, 2011, 01:59:27 AM

Thanks for your thoughts Borek